Apparatus having a static eliminator for manufacturing semiconductor devices and a method for eliminating a static electricity on a semiconductor wafer

ABSTRACT

An ion generator generates ions above a semiconductor wafer and the ions are directed towards a surface of a semiconductor wafer. The ions combine with static charges on the semiconductor wafer to thereby discharge the surface of the semiconductor wafer.

FIELD OF THE INVENTION

[0001] The present invention relates to an apparatus having a staticeliminator which eliminates static electricity on a semiconductor waferand to a method for eliminating static electricity on a semiconductorwafer.

BACKGROUND OF THE INVENTION

[0002] In an exposure process of a semiconductor manufacturing process,an apparatus is used, such as a spin coater or a developer, which treatsa semiconductor wafer with rotation.

[0003] Such an apparatus is shown in Fig.6, which is a cross sectionalview of certain component parts of an apparatus 100.

[0004] A support portion 106 which supports a semiconductor wafer 104using a vacuum chuck is located in a cylindrical container 102. A nozzle108 is arranged above the semiconductor wafer 104 so that a solution isapplied to a surface 104 a of the semiconductor wafer 104. When thesolutions is dropped on the surface 104 a, the semiconductor wafer 104is rotated by the support portion 106. Thereby, the solution isuniformly distributed over the surface 104 a.

[0005] However, as the wafer 104 is rotated at a high speed, frictionoccurs between the surface 104 a and the dropped solution. Staticelectricity is generated by this friction and the surface 104 a becomespositively charged. An atmosphere above the semiconductor wafer 104 isnegatively charged, as shown in Fig.6.

[0006] According to the publication entitled “BREAK THROUGH”, by Dr.Ohmi at Tohoku University, which was published in April, 1993 (Table-1at p.26), when a resist was applied to a surface of a semiconductorwafer using a similar apparatus, the surface was positively charged at3000V or more.

[0007] Therefore, transistors in the semiconductor wafer might bedestroyed and small particles might attach on the surface as a result ofthe static electricity, which in turn may lead to a reduced throughputand quality. Further, the finer the patterns on the semiconductor wafer,the greater the influence of the static electricity or devices of thesemiconductor wafer.

SUMMARY OF THE INVENTION

[0008] An object of the invention is to provide an apparatus having astatic eliminator which eliminates static electricity on a semiconductorwafer and a method for eliminating static electricity on a semiconductorwafer.

[0009] To achieve the object, in one embodiment of the presentinvention, ions are generated above a semiconductor wafer and the ionsare combined with static electricity on the semiconductor wafer suchthat the static electricity may be consumed by the ions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] While the specification concludes with claims particularlypointing out and distinctly claiming the subject matter which isregarded as the invention, it is believed that the invention, theobjects and features of the invention and further objects, features andadvantages thereof will be better understood from the followingdescription taken in connection with the accompanying drawings in which:

[0011]FIG. 1 is a cross section view of an apparatus according to afirst preferred embodiment of the present invention.

[0012] FIG.2 is a cross section view of an apparatus according to asecond preferred embodiment of the present invention.

[0013] FIG.3 is a cross section view of an apparatus according to athird preferred embodiment of the present invention.

[0014] FIG.4 is a cross section view of an apparatus according to afourth preferred embodiment of the present invention.

[0015] FIG.5 is a plane view of a discharge electrode of the fourthpreferred embodiment.

[0016] FIG.6 is a cross section view of a conventional apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described hereinafter withreference to the accompanying drawings. The drawings used for thisdescription typically illustrate major characteristic parts in orderthat the present invention will be easily understood. In thisdescription, one embodiment is shown in which the present invention isapplied to an apparatus which treats a semiconductor wafer whilerotating the semiconductor wafer, such as a spin coater and a spindeveloper. However, the invention is not limited to such an apparatus.The present invention may be applied to a single wafer processingapparatus or a batch processing apparatus used for etching ordeposition.

[0018] A cross sectional view of an apparatus 10 is shown in FIG.1.FIG.1 illustrates an outline of the apparatus.

[0019] The apparatus 10 includes a cylindrical container 12, a supportportion 14 and a down flow portion 11. The support portion 14 whichsupports a semiconductor wafer 16 using a vacuum chuck is located in thecylindrical container 12. A nozzle (not shown) is arranged above thesemiconductor wafer 16 so that a solution is applied to a surface 16 aof the semiconductor wafer 16.

[0020] The apparatus 10 is located in an atmosphere which is fluidtoward a predetermined direction. In this embodiment, the predetermineddirection means a direction which flows down from the down flow portion11 to the surface 16 a of the semiconductor wafer 16. In the case wherethe semiconductor wafer is supported perpendicularly, the predetermineddirection means a horizontal direction toward to the surface of thesemiconductor wafer. The atmosphere which is fluid toward thepredetermined direction is formed at least above the semiconductorwafer.

[0021] The apparatus 10 includes an ion generator 18 which supplies ionsinto the atmosphere above the semiconductor wafer. The ions fiom the iongenerator 18 reach the surface 16 a by the flow in the atmosphere.

[0022] In this embodiment, the ion generator 18 is comprised of a thinneedle type electrode. The needle type electrode 18 is sharply pointedas shown in FIG. 1. The needle type electrode 18 is connected to a firstterminal 20 a of a power supply 20. The power supply 20 supplies a powersupply voltage to the needle type electrode 18. A second terminal 20 bof the power supply 20 is connected to a ground. The power supply 20 isa dc type power supply.

[0023] The needle type electrode 18 is comprised of a conductivematerial which is 1 centimeters in diameter. In this embodiment, theconductive material is copper. The tip 18 a of the needle type electrode18 is located above the semiconductor wafer 16. The needle typeelectrode 18 can be attached to the side wall of the apparatus 10.

[0024] When a solution is dropped on the surface 16 a from a nozzle (notshown), the semiconductor wafer 16 is rotated at 1000-6000 rpm by thesupport portion 14. As the wafer 16 is rotated at a high speed, frictionoccurs between the surface 16 a and the dropped solution. A staticelectricity is generated as a result of the friction and the surface 16a becomes positively charged.

[0025] Here, the power supply 20 supplies a negative voltage to theneedle type electrode 18. In this preferred embodiment, the negativevoltage is between −200V and −500V. Therefore, the atmosphere around theneedle type electrode 18 is ionized and a corona discharge occurstherein.

[0026] As such, positive ions 19 a and negative ions 19 b are generatedaround the needle type electrode 18. Most of the positive ions 19 agather around the needle type electrode 18 since the needle typeelectrode 18 is supplied with the negative voltage and a strong negativeelectrical field is formed around the needle type electrode 18. Part ofthe positive ions 19 a may reach the surface 16 a of the semiconductorwafer 16 as a result of the down flow in the atmosphere. However, as thesurface 16 a is positively charged, the positive ions 19 a are repelld.The negative ions 19 b are carried to the surface 16 a as a result ofthe down flow. As the surface 16 a is positively charged, the negativeions 19 b are combined with positive ions on the surface 16 a.Therefore, the charges are extinguished from the surface 16 a. That is,the static electricity on the semiconductor wafer can be eliminated.

[0027] According to the first preferred embodiment, it is possible toeliminate the static electricity on the semiconductor wafer using theneedle type electrode which is a relatively small addition to thesystem. That is, an apparatus having a static eliminator whicheliminates a static electricity on a semiconductor wafer can be easilyrealized.

[0028] As the tip 18 a of the needle type electrode 18 is located abovethe middle of the semiconductor wafer 16, most of the negative ionsgenerated around the needle type electrode can be carried by the downflow to the surface 16 a. As such, the static electricity on the surfaceis efficiently eliminated.

[0029] If the surface 16 a of the semiconductor wafer 16 were negativelycharged, the needle type electrode 18 would be supplied with a positivevoltage from the power supply 20.

[0030] In the case where the support portion 14 can move up and down,the semiconductor wafer 16 is carried to the outside of the cylindricalcontainer 12 so as to expose the surface 16 a, and the charge on thesurface is eliminated by the needle type electrode.

[0031] The present invention may be applied to a batch processingapparatus which simultaneously treats plural semiconductor wafers storedin a wafer cassette.

[0032] A second preferred embodiment will be described hereinafter,referring to FIG.2. The same elements mentioned above are marked at thesame symbols and a description thereof is omitted. A cross sectionalview of an apparatus 30 is shown in FIG.2. FIG.2 illustrates an outlineof the apparatus.

[0033] Similar to the first preferred embodiment, the apparatus 30 ofthis embodiment includes a cylindrical container 12, a support portion14, a down flow portion 11, an ion generator 22 and a nozzle (notshown).

[0034] In this preferred embodiment, a second electrode 24 is locatedover the cylindrical container 12 so as to face toward the tip 22 a ofthe needle type electrode 22. An atmosphere 26 where ions are generatedtherein is sandwiched between the needle type electrode 22 and thesecond electrode 24. In this embodiment, a plate electrode 24 is used asthe second electrode. The plate electrode 24 is connected to a secondpower supply 25 which supplies a voltage power to the plate electrode24, as shown in Fig.2. Otherwise the plate electrode 24 is directlyconnected to the ground. The second power supply 25 is also connected tothe ground.

[0035] Similarly, when the surface 16 a is positively charged by thefriction between the surface 16 a and the solution dropped from thenozzle, the power supply 20 supplies a negative voltage to the needletype electrode 22. In this preferred embodiment, the negative voltage isbetween −200 v and −500 v. Therefore, the atmosphere around the needletype electrode 22 is ionized and a corona discharge occurs therein. Assuch, positive ions 19 a and negative ions 19 b are generated around theneedle type electrode 18.

[0036] Also, most of the positive ions 19 a gather around the needletype electrode 22. The negative ions 19 b and electrons gather on theplate electrode 24 which is supplied with a positive voltage (less than100V). Therefore, the kinetic speed of the negative ions 19 b and theelectrons is slowed down by the plate electrode 24. The electrons mainlycombine with oxygen and become negative ions (19 b). That is, morenegative ions can be gained in the atmosphere.

[0037] The negative ions 19 b are carried by the down flow to thesurface 16 a. As the surface 16 a is positively charged, the negativeions 19 b are combined with positive ions on the surface 16 a.Therefore, the charges are extinguished from the surface 16 a. That is,the static electricity on the semiconductor wafer can be eliminated.

[0038] A third preferred embodiment will be described hereinafter,referring to FIG.3. The same elements mentioned above are marked at thesame symbols and a description thereof is omitted. A cross sectionalview of an apparatus 40 is shown in FIG.3. FIG.3 illustrates an outlineof the apparatus.

[0039] The apparatus 40 of this embodiment includes a cylindricalcontainer 12, a support portion 14, a discharge electrode 28 and anozzle (not shown).

[0040] The discharge electrode 28 is comprised of a thin needle typeelectrode. The needle type electrode 28 is sharply pointed as shown inFIG.3. The needle type electrode 28 is connected to a ground. The needletype electrode 18 is comprised of a conductive material. In thisembodiment, the conductive material is copper, aluminum or iron.

[0041] In the case where the surface 16 a is positively charged by thefriction between the surface 16 a and the solution dropped form thenozzle, the tip 28 a of the discharge electrode 28 is laid to thesurface 16 a of the semiconductor wafer 16 so that the static charge onthe surface 16 a is discharged. Thereby, the static charge is removedfrom the semiconductor wafer 16.

[0042] In this embodiment, the discharge electrode 28 is approximated ata distance of 2 millimeters from the surface 16 a. Thereby, the staticcharge on the surface can be discharged.

[0043] A fourth preferred embodiment will be described hereinafter,referring to FIG.4 and FIG.5. This embodiment is a variation of thethird embodiment. The same elements mentioned above are marked at thesame symbols and a description thereof is omitted. A cross sectionalview of an apparatus 50 is shown in FIG.4.

[0044] In this embodiment, a discharge electrode 32 is comprised ofplural needle type electrodes 32 x, as shown in FIG.4 and FIG.5. A planeview of the discharge electrode 32 is shown in FIG.5.

[0045] The discharge electrodes 32 are comprised of thin needle typeelectrode 32 x. The needle type electrodes 32 xa are sharply pointed asshown in Fig.4. The needle type electrodes 32 x are connected to aground. The needle type electrodes 32 x are comprised of a conductivematerial. The conductive material is copper, aluminum or iron.

[0046] The plural needle type electrodes 32 x are arranged in adischarge region 34 which has substantially the same width as thesemiconductor wafer 16. Further, the needle type electrodes 32 x arearranged perpendicular to the semiconductor wafer 16 at regularintervals. Suitable intervals are determined by a voltage applied to theneedle type electrodes 32 x and a distance between the surface 16 a ofthe semiconductor wafer 16 and tips 32 xa of the needle type electrodes32 x. The needle type electrodes32 x are fixed in a support substrate36.

[0047] Also, the apparatus 50 of this embodiment includes a cylindricalcontainer 12, a support portion 14 and a nozzle (not shown). The supportportion 14 can move up and down in order to expose the semiconductorwafer 16 to the outside of the cylindrical container 12. The dischargeelectrode 32 is located above the semiconductor wafer 16 so that thedischarge electrode 32 does not to interfere with the nozzle.

[0048] In the case where the surface 16 a is positively charged by thefriction between the surface 16 a and the solution dropped from thenozzle, the support portion 14 is moved up to expose the semiconductorwafer 16 outside the cylindrical container 12.

[0049] The tips 32 xa of the discharge electrode 32 are approximated ata distance of 2 millimeters from the surface 16 a of the semiconductorwafer 16. This, state is then maintained for a few seconds. As such, thestatic charge on the semiconductor wafer 16 is discharged. Then, thedischarge electrode 32 is moved away from the semiconductor wafer 16.

[0050] According to this embodiment, as the discharge electrode 32 iscomprised of the plural thin electrodes 32 x which correspond to thewhole surface of the semiconductor wafer, the static charge can beremoved from the semiconductor wafer in short time, as compared with thethird embodiment.

[0051] The apparatus and methods of the invention for eliminating staticelectricity on a semiconductor wafer can be applied to each processingstep which might generate a static charge on the semiconductor wafer orto each of a predetermined number of processing steps.

[0052] The present invention has been described with reference toillustrative embodiments, however, this description must not beconsidered to be confined only to the embodiments illustrated. Variousmodifications and changes of these illustrative embodiments and theother embodiments of the present invention will become apparent to oneskilled in the art from reference to the description of the presentinvention. It is therefore contemplated that the appended claims willcover any such modifications or embodiments as fall within the truescope of the invention.

What is claimed is:
 1. An apparatus for manufacturing semiconductordevices, comprising: a wafer support which supports a semiconductorwafer; an ion generator which supplies ions into an atmosphere above thesemiconductor wafer; and a down flow mechanism which causes theatmosphere above the semiconductor wafer to be fluid in a directiontoward the semiconductor wafer such that the ions generated by the iongenerator reach to a surface of the semiconductor wafer.
 2. Theapparatus for manufacturing semiconductor devices according to claim 1,wherein the ion generator is a thin electrode which is connected to apower generator, and wherein the power generator supplies a power supplyvoltage to the thin electrode and is connected to a ground.
 3. Theapparatus for manufacturing semiconductor devices according to claim 2,wherein the thin electrode is a needle type electrode.
 4. The apparatusfor manufacturing semiconductor devices according to claim 2, furthercomprising a second electrode which faces toward the thin electrode andslows down a kinetic speed of the ions.
 5. An apparatus formanufacturing semiconductor devices, comprising: a wafer support whichsupports a semiconductor wafer; and a discharge device which isconnected to a ground and removes static electricity on thesemiconductor wafer, wherein the discharge device is comprised of aconductive material.
 6. The apparatus for manufacturing semiconductordevices according to claim 5, wherein the discharge device is a thinelectrode.
 7. The apparatus for manufacturing semiconductor devicesaccording to claim 6, wherein the thin electrode is a needle typeelectrode.
 8. The apparatus for manufacturing semiconductor devicesaccording to claim 5, wherein the discharge device is comprised of aplurality of needle type electrodes, wherein the needle type electrodesare arranged perpendicular to the semiconductor wafer at regularintervals, and wherein the needle type electrodes are connected to theground.
 9. A method for eliminating a static electricity on asemiconductor wafer, comprising: generating ions in an atmosphere abovethe semiconductor wafer; and causing the atmosphere above thesemiconductor wafer to be fluid in a direction toward the semiconductorwafer to combine the ions with the static electricity on thesemiconductor wafer.
 10. The method for eliminating the staticelectricity on the semiconductor wafer according to claim 9, wherein theions are generated by a corona discharge, and wherein the coronadischarge is generated by supplying a dc voltage to a thin electrodewhich is arranged in the atmosphere above the semiconductor.
 11. Themethod for eliminating the static electricity on the semiconductor waferaccording to claim 10, further comprising slowing a kinetic speed of theions before the ions are combined with the static electricity.
 12. Amethod for eliminating a static electricity on a semiconductor wafer,comprising: providing a thin electrode which is connected to a ground;and using the thin electrode to discharge the static electricity fromthe semiconductor wafer.
 13. A method for eliminating a staticelectricity on a semiconductor wafer according to claim 12, wherein thethin electrode is spaced from the semiconductor wafer at a predetermineddistance during the discharge of the static electricity.
 14. Anapparatus for treating a semiconductor, comprising: a rotation devicewhich rotates the semiconductor wafer; a nozzle which supplies asolution to a surface of the semiconductor wafer; a down flow devicewhich causes an atmosphere above the surface to be fluid in a directiontoward the surface; and an ion generator which supplies ions into theatmosphere above the surface.
 15. The apparatus for manufacturingsemiconductor devices according to claim 14, wherein the ion generatoris a thin electrode which is connected to a ground.
 16. The apparatusfor manufacturing semiconductor devices according to claim 15, furthercomprising a second electrode which faces the thin electrode and slows akinetic speed of the ions.